SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '6b560dd3b7bf96ff35f371437c0a6e12c1cf8b823b3397788640011f2d0e9e6a' 
  AND token = '0CvtVLTgb0tZfIsuK0UxPTZgy6p0WBErQX+06o4kdp0=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00043

JSON explain

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