SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '76f2edb40421c78d641a5d763b49ecabc10ca2c4a4191aaeeb8eeb38131add66' 
  AND token = 'XTQk2IlXmxWoOQfWJGrMOIBvgHZtSGmL3mw5fVDl+ow=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00028

JSON explain

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