SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '2c4c13abef8e6610bcaf6cd7fa9b435a8ca4aee65f01db7d365c208a2cc97f87' 
  AND token = 'bbUHTPn5rqr+Ym1ic63sZztvT2irzwWo7kiaADsFlko=' 
  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"
    }
  }
}