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SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '3d6fdb4ed2f6b824497b34b03c9b453af906399a9bf7bdfba013afe8ba66b104' 
  AND token = 'MklWjb0ibrkWvqrb5OejJK8cc4dqQAWw0tIG0vqKD1c=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00033

JSON explain

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