SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '4a70ff02929200931b12546ebc03d77552db78b84428051f473daa354b4010f7' 
  AND token = 'BRBkNouQ5U+dR7FwtXjRhqbMarm8Nk6tULeTZVen7Vc=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00030

JSON explain

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