SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '81157551b00275d7786f5ed7f5eb9c509a0cc335df203daa70ec930ca5c554a8' 
  AND token = 'dFjQ8uL76d37cC+hcFOBXuvLvIEm0JHGp9dpvQTOJVE=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00024

JSON explain

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