SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '89edc4f368512f0d2af980efbfc006b7adf6018fb5a6a7f786b6e75b69a1337a' 
  AND token = 'L6+CvO77LtE6nbmE53HdFZiKSpkUBykr92qkaWPiUXk=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00040

JSON explain

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