SELECT 
  1 
FROM 
  cscart_aprillock_keys 
WHERE 
  key_id = '52226c8372add0b8aab640d795898a68bb3fe1ca5373cdbe38cf2c7b3400278c' 
  AND token = '7MxP5QRJF+0wH9+F98rBZCDa8nRAU01wdjgArv+mq3U=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00027

JSON explain

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