SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '5e0838978d211cd9754dec5382a60e6f4c3c82c66f5cff5b9fe6fbddd3f850dc' 
  AND token = 'fRUSQZX+bfFzKPfYvACgP/Dx0fRNCmSVnsy+/uGKCzk=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00039

JSON explain

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