SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'a5afef06fcfc8c1c30ebc11acf442be2cf524dffd17029a4ed79c05c76d0b427' 
  AND token = 'j7to18LT1bNPzQOct5LvanzrzS2AdfZChP4paGas+6I=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00033

JSON explain

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