SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '9794ca15837a02ef5b1f68414827d248c810161ce30d26ced1f14164fdad6386' 
  AND token = 'QW6b+ySWkMIqdsF7fVkm9/MrBpv7vpT2vObrtAWYnmE=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00029

JSON explain

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