SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '73c617f7a6f32256174e73c96489350899370d0eac1656777ed10971a012e6ac' 
  AND token = 'ZHaHcokW1EFUWpDXzXbS6TOWqm3ltctMnWh7V0STVnE=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00021

JSON explain

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