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SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'c56a61546e51d1d68b5cbf6f0404cb9d346868b7864ee1fed6f1277bbbfae702' 
  AND token = 'Cvlylc6NAUtcdtum7QEZ+0Q+5iPaNqoZ9YFe7UE8Z88=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00025

JSON explain

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