SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '87bc90798a6919134d8a6761f10bb9044ab564964cd1928f2e491957a94eb88a' 
  AND token = 'JLlvI1lSXqAaM2dDBGau96MdN6LJKzK0Xy+4uNUBKW8=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00041

JSON explain

{
  "query_block": {
    "select_id": 1,
    "table": {
      "message": "Impossible WHERE noticed after reading const tables"
    }
  }
}