SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '4fbea7dd1e916d3fd59564992b128f4221630133e7821ad7a63157d263910b2d' 
  AND token = '94gTyrEDXuhVNQdSpNfFv+IP8qbJ9W+Cuv9DuA4Ls58=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00042

JSON explain

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