SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '6c22f727cf778d39e49357badb07fac79e03c98c0f87d1f1718f49d16635b448' 
  AND token = 'btqLueIVcvJBzl7mMeZhJwFdf3p7D/JXhFCxT2gmcCY=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00044

JSON explain

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