SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'bc7308bb5c8f5568910c51e6f2ff902cb4a439f27fb51d5fe27fa7e410a49bc6' 
  AND token = '0K+bt6P/UNjmC2MT2jsCPZHWsyxXZPh7p6wPiRVvfTM=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00018

JSON explain

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