SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'a23265df197bc5663756c62c93a7bc57da79d2e73afb2dbbccc429859e27bb58' 
  AND token = 'PSyttVNhKN7IvCan0Wpc+J1mn11OMJgpKwo407s815I=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00036

JSON explain

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