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SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '878c2139df6490d8d406a7c4c92156703546f6c732221b72ed65db2e9efac3ec' 
  AND token = '1U8K+f8jtB2UiMZrbaLMWbHUYd93MiVD+KMTOK1RZUw=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00023

JSON explain

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