SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'eff8b73fc75b96a74a65208ab7c4259ee42ca010b768305ee45327ac7e5a0347' 
  AND token = 'DrolBXCAjPSaEOzsElUZGCwPZpgqkf3KEp2snvuqJwA=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00025

JSON explain

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