SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'cefc0ff82a12ae1ef35aea15c4c189500098a3800c33536cdf77d90c76f51f92' 
  AND token = 'D2TknZYWQH7ZcNQE8TcDQQ5cIKzXywXgh8XUUeY+5gE=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00041

JSON explain

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