SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '51eac93ce8d81fbe7ed6a31118426ee6b53274e511fe878d93d9509dc9f3e437' 
  AND token = 'h8ZzXcRmf8epAbDlX6nSR8gkWurc30JSIakcFSINats=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00044

JSON explain

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