SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '3f45135747a82424a4d27efa34e081d84ed56c53d9d0620cbfa0d599cf2d6c6b' 
  AND token = '1PbX8ZPZ+Zdvg9NCL+Scgct7hzJ8mSwYYuIb6X1Os18=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00035

JSON explain

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