SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '893929d77a410c62fc50098f11e9bcc960100644debb6a4728e17748f336ee63' 
  AND token = '5baFbbpzAlXh/FzZvgm/nHEkWLWLPkHyOam4Nq9Jpws=' 
  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"
    }
  }
}