SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '420ccca8a2f57f4aacd6e245d339830b5682d2228d63df060fa0f9e1df19e9d0' 
  AND token = 'Ji6jGzXMFWaJXLOLbdvkwW2pHLpJvzepzx136MfPWF0=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00024

JSON explain

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