SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '99aaabba682aacb01d7930fbe6a0048c618349055da644535d91e05918fc8263' 
  AND token = '9+otiADuRZ8dK7YRhkVyeCjaWR17pceea/JBTekUEEY=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00043

JSON explain

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