SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '8c9b00a4fee0a8c69c886de4a0277c69ff513dfed53eb56eba4a8bab8a37affb' 
  AND token = 'BCGNDRxiqSKfnICdRxG2wGpiVSlJJVhyRRQTJe1N8ko=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00039

JSON explain

{
  "query_block": {
    "select_id": 1,
    "table": {
      "message": "Impossible WHERE noticed after reading const tables"
    }
  }
}