SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'a3d244f9dba0d2b8ea3369e7f0085c379a864d5fb0c7eecc1727f8c230af4a95' 
  AND token = 'K/NMUMiLrs26ttXoxY1qNkIANoOjmbNW7SAHAsKAzmQ=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00032

JSON explain

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