SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '5d6704cbea34e265ae8d347377330e4456248c1d4b2819e140692785a524c28f' 
  AND token = 'fFKhdbTCEpaG081tObQjbet36LMomZ3PP8uX/xbDtzc=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00023

JSON explain

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