SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '76b9caa56b36ea74813d86ad7df18cbe8360728b6fa9a3c31a7e10d4254432b5' 
  AND token = 'Nx0sy6NWFCsr1kv+Ka2GI5WgnRxSKa+f3ChXcI1tkLw=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00031

JSON explain

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