SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '5a76146133364b9e776cf094e139fa2d8f3c0589ace152f2125c06a7a741d114' 
  AND token = 'vhowJAOFCzrzQkjL1YA8UJCXHZrXK+2fOEuZdB1Ua9c=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00030

JSON explain

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