SELECT 
  1 
FROM 
  cscart_aprillock_keys 
WHERE 
  key_id = '4278dd91fbf8fc9efe28c654eaa099c68f2b497866f246e1f85638af5f89e1c1' 
  AND token = '6pNRGQC4pztJx6W95hiwI7dOXda1DkE/HWfycRxIKdo=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00025

JSON explain

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