SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '408641ed33bfe7a83dc0e6253b304bad1c9bd526300e6f59c666514a3d25eb64' 
  AND token = '14AeWb8iu9rLRtIDmrwMgn7XzrqjcRqrzfUjabw80Ag=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00041

JSON explain

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