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SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '4e2c2f7ae2cd60b41c5aa9cd79354e11982e2b40f8621a92a2ce26f335589a2c' 
  AND token = 'Nvj37ekMRDJTxHl+Qd9wg2VTXcSdpbmuyvsvg8r1RiM=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00027

JSON explain

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