SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'a641fa216dee30e730b9e99f0c9b6d4aea2a0a7e944888505469980f42ea5bfe' 
  AND token = 'kzPHd6mI1RM5mXZoFDdVzxxsA9H3DWJO7UVLe550Ld0=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00023

JSON explain

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