SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'a5fdd085c3c59627c1afe8cb8059ed55ef8c012a613cb77ed04ec4fbbfddd3bf' 
  AND token = 'k4VIbv8yajUeEIx8zdDw1HIKIig5BouXCBFVayAgfPw=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00031

JSON explain

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