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SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '37be644dd12c44f4c9d1f6c836f84327a48ae1d50b121e29ab16c283ca5e0342' 
  AND token = 'ClFFlJfjQkZxe7CQSGxTIcKkoLfGIXgRZlcUWLTGE8A=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00024

JSON explain

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