SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'f2c6178bdba4e2da100f1d91766a495205702e14067921195303aa943f3a9cbe' 
  AND token = 'RcsStv+i+LoQ3X0rFaLP2I5qjzyWF5ztLz2HHGWURAI=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00025

JSON explain

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