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SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'c13ab15c5e0a7929c50fff000e23b478829e3f4d7b01a1973fbc43851a75cc87' 
  AND token = '0MNfneAad1ujl2h0opquc0fFngN2LLGvzGqCGx39Sdg=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00031

JSON explain

{
  "query_block": {
    "select_id": 1,
    "table": {
      "message": "Impossible WHERE noticed after reading const tables"
    }
  }
}