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SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'e91b0b8b07d6bc4ed0c71b348deec18804484ea91ccee56b9d9e783fd18ecf51' 
  AND token = 'OnQuLHwbXDq3XBHwUCDb+jUN93kgcK8U8OtHDZGzCIk=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00018

JSON explain

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