SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'a4bf13f02854541e5b5571d24fae0a807dfff94bf25c10d93360f36449527d36' 
  AND token = 'u7bmTGpDG/6X8jCFiDm+NGLjTDLbBp/RY2XPf+sy5Uw=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00039

JSON explain

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