SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'b9980e1d8b405d90aa1bb8f10b294f618eb186721c011cac72e0f56c2a435e1c' 
  AND token = 'AelMKXAMgC3cGWjmibXOPI7tPs0+MdA1cNu3kWw3ueU=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00028

JSON explain

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