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SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'd798b6d3f2df3c1cb7e4df20cf84b8c3fb7e099703b7f91f42d6ca7bc7537f50' 
  AND token = 'zhsdDM6+DvNgN/4+cNJQdZZ+rrwqkCZ+WRQzakKd9h4=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00047

JSON explain

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