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SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '316e9bae815e812784d34288aaa1d9ec93acfc6daa36f56e1df1dcb2bf75555f' 
  AND token = 'kk/yy2eiL544DF+4U/xy4X7GyxnC7NM5nxfEsuj8Jy8=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00022

JSON explain

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