SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '712590f66d5f02857e587ab4375f6ef69a5f3771631bcdb280cfe1d8fde15624' 
  AND token = 'SJlgLlLzu/rEfsSbSkGFCxoSLboz9ko5TacBOf6fqbg=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00027

JSON explain

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