SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '8dc17557289cd6589e57f6d4af1e041a901e46d721cb9e618a314abdbfa4685f' 
  AND token = '1RONVddKLSSvWfK65KmmQP5+FaO73Ljjul2J+ZuPFf4=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00022

JSON explain

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