SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '83867a5e58e993568144efb10d3e575bfca4d5214b4194508156bc7d7339b54a' 
  AND token = 'RBj+/XQwC6Yqe6IV5/DE8qmCz1lgvgUhuIQ+1cL50Ng=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00019

JSON explain

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