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SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'dead9bbc76af6d3c4bcc2c97084ea699be08fb35b9dd82ae1e50f7bca0e113e4' 
  AND token = 'c+N/yzKiQURi1Q4HchpvEP7aQh3VWYRyXZKMe+CbFCw=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00018

JSON explain

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