SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '6829ec38cd44ceb1caec83bad4a9429e46671d7420c3a245afd0a0272700a7c1' 
  AND token = 'qFQwvfasX+Nlqia6MfoaV832HTU1UBY03Zo6zUdHUew=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00045

JSON explain

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