SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'a79adb10b8160a8f33994884c693e2aebbd77ce2e5536869a5e0ea965cb7f6fd' 
  AND token = '1zu0yEWdSGUJzjeTAA/3pd8DPMKs+xscfMvDNtkSOUM=' 
  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"
    }
  }
}