SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '3685d4c871580e5be94552e7a373ab99e4f220db5e54c09537dc0d6ae35fd8b4' 
  AND token = 'W7wQT3USiTtbv+ZXn3VFnmcCmnbMsFwg72LmagvvI7o=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00033

JSON explain

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