SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '38a367cbef979036be85731532f48b57771e17fd8e8cd5635f2756efec7848ba' 
  AND token = 'MtXdKiqPowUWIMCS8Zc7c9fhyErgcCJagSApbfmzK5M=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00032

JSON explain

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