SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '2bbdf01a3b409b34185187f5a89483adbb9eb5981893059cadf8dc1d506fbe50' 
  AND token = 'DkajTfMldnM3Fd2swreMouGzf4K2neWJwnDtDSGWtv4=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00038

JSON explain

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