SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'e8eb329b21318ee230ad3948847f1e217878d44a025bbea04283b0085a8451cf' 
  AND token = 'iaOLAtvmsqa/BIjnFCnAxh4wJ7h1IQdOJmEn6D3ISRs=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00020

JSON explain

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