SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'd15a18ff32daa7fa4975c284185aeacf70615bb43f15c892ba94b0baecd50586' 
  AND token = 'PTHrmAaUHsRcIkIgHB1Xwpehb8++JicybeUq5Fk3ozQ=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00026

JSON explain

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