SELECT 
  1 
FROM 
  cscart_aprillock_keys 
WHERE 
  key_id = 'fd51527bb81984e73b52e6de9f5b80b25884951ef6335be92e57694b014167a8' 
  AND token = '4XS1+9FsN100yk5WiXBDMwr28JVWyPYZDFejry5DW38=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00033

JSON explain

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