SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '46c5d6290028c7eec24398cf346352577994f863840b1536f3e36a19b91e0c41' 
  AND token = 'KxYcXZOvylWnwrPoVczC3moQvQjRpvebE60wgreHoXY=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00026

JSON explain

{
  "query_block": {
    "select_id": 1,
    "message": "no matching row in const table"
  }
}