SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'f0341796edf4c872b38ab40467992e7164743e1cc9e0b42700021b51bde6936b' 
  AND token = 'pDcSRcGLermRF+aN1Xqwc4JST+Ha65EFiEh/5PqqDWw=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00049

JSON explain

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