SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'b9ef4b43132401d5d605481312dfffd81bb8abf767cee9836c7e4465271daa10' 
  AND token = 'hCtu5VLcogm5nPIdDU5SOuQUc4t5t863DiYuYmnCnpw=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00038

JSON explain

{
  "query_block": {
    "select_id": 1,
    "table": {
      "message": "Impossible WHERE noticed after reading const tables"
    }
  }
}