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SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '6d12212f0ebcb5c8dd2c7c6f3dfa5173e60dd27d845c5e753bc8a9df41953a50' 
  AND token = 'K5yPfnAERo+bPSicBAsUjmZF0OuELi9mJsZ29ZYb1Fs=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00024

JSON explain

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