SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '3f706a7d9f38b81aa38545390dab87ff25ea4eff9ddf9e616f759790d1d28a02' 
  AND token = 'QD35574rFGKdIjtvjVfR2K8K3xJgBid9TTX11CRTm1g=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00041

JSON explain

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