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SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'eae9f4f3c7c93270ffa7b41cf52f5b266009d9d60ed7c52f06d5c50ddda9eac4' 
  AND token = 'uS4T/9ePCWC2UB8rwFBLP8o4bI80rn91VP4QTrl+rmw=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00021

JSON explain

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