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SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'ec75ef7cab553cdffc96e15fb85cde3e39de3fd60434ab9fca386f2c4ca914bd' 
  AND token = 'l6pGc9d3lQtTRjiiCA5L2YjbAFwq0+xZ+Hm1hfnBB+M=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00028

JSON explain

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