SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'c3d892fb13449c73ca0f4f1ea76d1848e134422192a9895e02804208a92b5a8a' 
  AND token = 'op7GrnwJIeJB+YFm2adcociy/P/LzPQNLbLeywzY058=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00053

JSON explain

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