SELECT 
  1 
FROM 
  cscart_june_setuplock_keys 
WHERE 
  key_id = '546eb8be07cd9ebcbf634c56358d58b679f1c451e2b0eca276ce1f849200782c' 
  AND token = 'ZI2q+kFdgb26v8PIgV12kJobv3hnNAWP/WRDfblowzg=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00027

JSON explain

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