SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'fce427ca62fd43828031d6b337291513d5fbe4469288fc8dcabcb7e6fbe1f940' 
  AND token = 'rGw+lzg8dZTz35EwUH58xSSW+/+6pBmgFGxPivwspxU=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00044

JSON explain

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