SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '59986da61871574851b73140f3c4ccc8d1668bf69d6a1815de5d2bb35326f334' 
  AND token = '1Rbrc9uLHG7vYFN+Ay+kkCMql/OOI3pmGW0ztjNMpyg=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00027

JSON explain

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