SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '0a77ad0b104561645eadf70967fe0b0c6da9130e890649f720c27dde9eb4d5b1' 
  AND token = 'qwViVCTxRuOq3EKkLDpiQ8OmCXnHYzAVTzkvDdwjhYw=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00036

JSON explain

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