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SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '44cdfca705b3cc80e546035363f1ba20e06a5f54b15d1d31a49173347d714baa' 
  AND token = 'LW3eFbr/ovE+sK7lcf8zN71VXfdOnh3BKbvPw+btKHI=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00023

JSON explain

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