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SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'dc3e54e1b471535fe05d93ec06494aa73bd91955adf0a8bdfdd650b3fe6e2d2e' 
  AND token = 'UcD6AVZhf4oQnIg1YDlvM/mzg81ATSmQ5gZQCA8QiQs=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00019

JSON explain

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