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SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '408e264aee5874a173071f3d840dc0597be28135acdbc47943017b1d1c5a2704' 
  AND token = 'Tqk/nR5f7nchp6PnRnXckl510HKnR3RT2OYQ2d/1cs4=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00023

JSON explain

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