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SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '4c520f7bb2ccbc54a80eff3d0fa2102aa4091e898b12acd3e0d4b85e8205f18b' 
  AND token = 'Cs+d9z/By/d7uxKjzfPrqEoeKyKuZIC1SLjh6mrTpDc=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00018

JSON explain

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