SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '5aeff29b324f09b706775c110502cb7dca755d91def40d043ede484c67322ddb' 
  AND token = 'x4zjMmrVMxRtsCdKUicjw/Pw1kYsk7lLUYz+JIrWsXs=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00037

JSON explain

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