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SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'df2d5d1fe9c897e300cda0035ad2e1c3deba3287dd413471d26f7275254bd366' 
  AND token = 'y0jeJpUTiLaJzaPGaZcurf8LRy/ICCE7O0nT4ot3QZ0=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00018

JSON explain

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