SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '71568d5b17e9f43587651822502a541e1c7e0f97b73a092558803168ff20abcf' 
  AND token = 'DA8qVApLCv/XSnDdmXnPM3uY2rglMKxgE/+jwlvlrAU=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00020

JSON explain

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