SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'c7ca91c81dc45f37d7f515c2e6991c485d6b3ff598ff02b9bc3692772d3b70ce' 
  AND token = 'KTvWzlQLXKiq5GSnMlh9HB+3rF0UNRcv8w/izTlSI+w=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00033

JSON explain

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