SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '91f632b975874815ec38b5bf199cad88657283f44282761b641a64485442a22f' 
  AND token = 'MkfHRlNhfQ/ZOmIV2eNKmDzLh/8AINyToURGijnANRM=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00018

JSON explain

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