SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'cb6af3980af401f6d8fd890da029a1c6a7d2a783ae2f2f7072d1ef5621f9dcc3' 
  AND token = 'MCcdjNQqFJjkmo0wiDkAJLG7/UOXGtEz1NmRbucbhK4=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00043

JSON explain

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