SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '989a331ebc512aa870e9ed1dda961394eb97bcbe440a3e8d28dc1047e6756bfe' 
  AND token = 'P6WDfPXzh5fxzaybCPoKeiqxicU1pyp9Tm91rkcE2Qo=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00042

JSON explain

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