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SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '424ba3b6b0fa1837ae8ac3b684f4f29b33acefb78ce75abcc6d7aae2701d93a4' 
  AND token = 'WnYQ/xLcdAYacO/0JDkhuvq5dV3vd9RryPyD+i1xz4E=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00028

JSON explain

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