SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '8c2f5a0c788aec2461802961178287de1ba1ea56092a47f443f0c1d2652b4037' 
  AND token = 'zxn9u2uN7zUxRXI0UBzkPM6hEa/gaWRsxvUXcOUMmOk=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00035

JSON explain

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