SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '9433c2d74cf64fd808c96b3f9daa459c1d56017dd0879bf0542adf2667fec589' 
  AND token = 'mkhCDPjcwNsWEYI9XTQfHti0BWzhNRXwZF/njvh0N5g=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00034

JSON explain

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