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SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'b76c5dc699a7ddf933ed2e8c5c5e7cdfbd1ab5563c917b5ee9c72eb54c427bbf' 
  AND token = 'mjfBPg1htZxIX2byvGko+uLMoFEy9Tg3G8j/Ayp3o9A=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00028

JSON explain

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