SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '90d459c87e55b662a5efe75b44667ca6b2d0d60ffbc014d6fd95d46a644465e5' 
  AND token = 'ftUuGEvPleGJMCDIxeaM8MzrvWllPpu+454dpzQozsc=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00031

JSON explain

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