SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'b703c976ee4e2424aa556809edd13d8e8d97f528205d8c771fc0fe4cb1c34ced' 
  AND token = 'k81r0uT9TsL09zYLmHKv/ccUv76W8w3ySy9f6g6OCLI=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00019

JSON explain

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