SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '3c1e4759884b51a81e626f266fd0cf3bc825d14b60785253038fa0e0bc225a19' 
  AND token = 'KUVaUkugWHzjvnOPeU2hknrbpKmAl+jgTvqYbsB+b74=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00024

JSON explain

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