SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '0612f7cbbae0d96fa418333748d0d12a01b2a47e9cf274a5c2ed727fdb3109b0' 
  AND token = 'GMEhM52zP7vWtqCIgnvB4AtTGpNPGewImcwppjxOBJ0=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00019

JSON explain

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