SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '9e4619e0d1160e362ecdab88fa34f12eb20de0a849b00bcf1a374058a64ce544' 
  AND token = '528zWADAdoKhn8YIuEqJpgo5nAARKpguEE4KN7DTZMY=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00042

JSON explain

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