SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '8f89bff6eea8bb01e50616b109b6cba364ec5994407cb2a8a52f9f55d1320f73' 
  AND token = 'kHcTZvIqMJxdM8kB1B4KSCsgb4caOBR1I747rzujAv0=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00035

JSON explain

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