SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '5a48878b4cb2452b09c425b1e1be60172eb329114bbeb8ef994b37a2f0071ce6' 
  AND token = 'dtMi1dCZRPnMgg+umj6gHt69wmykG8cMMCnocc2W4uA=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00021

JSON explain

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