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SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'c1c0a35986ccd04d36cbdf5fec6f08b38969d59d4052d1759f14c1a58c5a64f3' 
  AND token = 'RQFgF3WIBWB8ssc1GhEcT+/4+8lY1jeFP9daDftu+jQ=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00025

JSON explain

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