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SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'b3dd6a11c75a2b8734aaab8f126eaf72d92502abc12cc96ff30b46c08d2fc7a2' 
  AND token = 'HYSAhKVSVpqUf8rCZUUmI/3glMjPkgtWIhMkDEapSJE=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00021

JSON explain

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