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SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '681fa136250384796ba1aeec73ac7e1b55e04901f1006eb8c430a81883f16c97' 
  AND token = '43p+gmggmZk/clDrm82Xj9RSY064snXw4NGGrCQIgFo=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00035

JSON explain

{
  "query_block": {
    "select_id": 1,
    "message": "no matching row in const table"
  }
}