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SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'ac2aa233f21ccdd1da51527af1a6c18f4cec03beb6a0ac2ff48d4ee95247e3e1' 
  AND token = 'NiDsGA9LunC9D8XtHzSuhE+Hxgy0UVz84YTDpD0lvRA=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00023

JSON explain

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