SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '66e6fe57091b3fc2c12896638e551a22db42c265986c1f09a1de8cb36a47f973' 
  AND token = 'qZB75mJqtoSz+S/W1eNZxl7fuXPCQuKxtVEejc9ckFY=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00018

JSON explain

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