SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'f7b0638a4b3406176c90713050592c10509da5136031182ce5115557e8d53308' 
  AND token = '9+wDNYmEnuXlKWQwMJDETpwQKmTGAG4VpeFMKTtHcro=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00043

JSON explain

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