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SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'e8a9780f1bcd51afe8487486f0e207956759e77cb673aebcfd7bb34d771f42dc' 
  AND token = 'gRLUtSSBUVPPlUPVmNrm7fRMf4oYvVAP+E8FMkj+Zpo=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00024

JSON explain

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